Inspection of electrical characteristics of an electric circuit such as an IC, an LSI, or the like formed on a semiconductor wafer has been performed by using an inspection apparatus. The inspection apparatus includes a probe card electrically connected with a tester, and the probe card has a number of probes disposed on its bottom surface. The inspection of the electric circuit is carried out by bringing the probes into contact with respective electrodes of the electric circuit on the wafer and applying electric signals to the electrodes.
However, if an oxide film is formed on a surface of the electrodes, it may interfere with the flow of the electric signals, resulting in an inspection failure. Further, if the probes are forcibly pressed against the surface of the electrodes to allow an electrical conduction between the probes and the electrodes, it is highly likely that the probes or the electric circuit will be damaged. To solve this problem, there is proposed a method involving the steps of bringing each pair of probes (a probe pair) into contact with corresponding one of the electrodes at a low pressure before starting the inspection; applying a high voltage between the probes in each pair to thereby generate a dielectric breakdown on the surface of the electrodes by a fritting phenomenon (hereinafter, referred to as “fritting”); and thus achieving a good electrical conduction between the probes and the electrodes (see, for example, Patent Documents 1 to 3). Here, the fritting phenomenon refers to a phenomenon in which an electric current flows in a surface of a metal on which an oxide film is formed, as a result of the dielectric breakdown of the oxide film by means of applying a potential gradient ranging from about 105 to 106 V/cm to the surface of the metal.
However, since a great number of electrodes are formed on the wafer to be inspected, hundreds to thousands of probe pairs are mounted on the probe card. Further, for the fritting process, a high-voltage power needs to be supplied to the probe pairs.
Conventionally, the supply of power to the probe pairs has been performed either by connecting a power supply to each probe pair individually or connecting a plurality of the probe pairs to a single power supply. In the latter case, connection to the power supply is switched from one probe pair to another in sequence.
[Patent Document 1]
    Japanese Patent Laid-open Publication No. 2005-5331[Patent Document 2]    Japanese Patent Laid-open Publication No. 2002-139542[Patent Document 3]    Japanese Patent No. 3642456
In the former case, however, since the power supply needs to be provided for each of more than hundreds of probe pairs individually, the size and the price of a circuit for fritting increase. Further, in the latter case, since the great number of probe pairs need to be connected to the single power supply in sequence, it takes a very long time to complete the inspection.